Filtering Power BI Dimensions with List.Contains

I don’t like loading up a slicer with dozens or hundreds of items that have no corresponding records. The same would apply if there was no slicer, but the consumer wanted to filter using the Filter pane. So I’ll filter the customer table so it only includes what I would call “active customers” that are shown in the sales table.

The most straight forward way to do this is by doing an Inner Join between the tables, but there is another way, using the powerful List.Contains() feature of Power Query. And what makes it so powerful is not just it’s utility, but when you run it against data in a SQL Server or similar server, Power Query will fold the statement.